1. Field of the Invention
The present invention concerns a constructional building set comprising gear box casings which are provided with guide grooves and shaft passages constructed such that transmission elements can be inserted into the guide grooves from the outer side of the gear box casing so that the transmission elements are positioned in alignment with the shaft passages.
In connection with constructional building sets e.g. for the building of toy vehicles, cranes, machinery and the like the gear box casings with inserted transmission elements perform various transmission tasks which can be achieved using known gear wheels, racks, chain drives and similar transmission elements.
2. Description of the Prior Art
Particularly in connection with toy constructional building sets it is important in view of the motor function of the child that these gear box casings with transmission elements are as simple to assemble as possible. Thus, the Danish Patent No. 161 868 discloses a steering mechanism comprising a rack assembly including a rack and a gear wheel which can engage the rack. The gear wheel is mounted in a housing through which also the rack extends, there being provided a groove through which the gear wheel is inserted into the housing, said groove being closed at one end in a manner such that the gear wheel, when inserted into the housing, is positioned in alignment with shaft passages which are provided in the housing so that a shaft can easily be inserted through the shaft passages in the housing as well as the shaft hole on the gear wheel. When the shaft is pulled out of the housing and the gear wheel-again, the gear wheel can thus drop freely out of the housing.
The object of the present invention is to provide a toy constructional building set comprising gear box casings which enable and facilitate assembly of the gear housing, the transmission elements and the associated shafts to a higher degree than the prior art. Another object is to provide a toy constructional building set enabling the shafts to be pulled out from a mounted gear unit without the individual transmission elements dropping out of the gear box casing, thereby enabling easy and quick transfer of a gear unit comprising gear box casing and transmission elements e.g. from one toy structure to another.